1. Field of the Invention
The invention relates to the field of composite reinforced materials. In particular, the invention relates to transport of highly compressed gas with high pressure tanks reinforced with composite wraps.
2. Related Art
Gas transport systems exist for the movement of natural gas or other heavy hydrocarbons from the field to market. Steel pipelines provide a traditional system solution, but are becoming more expensive to install as the pressure and distance requirements increase over time. Removal of gas from remote locations using pipelines is expensive and sometimes politically impossible. Deliberate destruction of a portion of the steel pipeline due to terrorism or sabotage may cause a propagating ductile fracture or ripping failure in the axial direction of the pipeline that is expensive to rebuild and repair. Also, problems with multi-point collection of gas and delivery from those remote sources raise the cost of transportation using traditional pipeline methods.
Collection and transportation of gas from offshore sources to onshore markets using pipelines often poses regulatory and environmental challenges as well. These delays inhibit realizing immediate return on investments made to find the offshore sources. This increases the cost of collection and transport and often prevents the gas from reaching the market.
Pressure vessels may be used to transport gas from remote or off shore locations. However, present methods of manufacture produce relatively heavy modules that are expensive to transport. For example, all steel pressure vessels designed with Grade X65 steel having a 42 inch outer diameter and 1 inch wall thickness approach 437 pounds per foot. Not only are the modules difficult to transport due to their weight, the pressure vessels may also suffer from vulnerability to physical damage during transport. Other challenges include corrosion due to the environment and stress corrosion caused by reaction of the transported gas with the material of the pressure vessel.
Traditional practice attempts to lower the cost of transport due to weight and durability concerns by producing transport modules with stronger and stronger steels. In steel welded pressure vessels, hoop strength may be calculated as one half the longitudinal strength. This proportional relationship results in utilization of higher strength steel at higher operating hoop stresses to accomplish increased pressure design requirements. Unfortunately, these stronger materials tend to suffer from increased brittleness, corrosion, and difficulties associated with welding.